This invention relates to apparatus and methods for positioning and connecting one part relative to another corresponding part of a piece of equipment.
Frequently industrial and other operations must be accomplished at remote locations or in hostile environments. For example, many projects in the area of mineral exploration and production are carried out at considerable depths under bodies of water. In such operations, it is sometimes necessary to connect and disconnect associated pieces of equipment at such remote locations. In the field of oil production, for example, an undersea blowout preventer stack may be located on the ocean floor. Normally a lower riser assembly is connected to the blowout preventer for sealing the well under certain circumstances. Hydraulic lines and other types of lines typically connect the lower riser assembly with surface equipment associated with the well. In some situations, however, it may become necessary to disconnect the surface equipment from the blowout preventer stack. Should a severe storm arise, for example, such a disconnection may be necessary to prevent damage to some of the equipment connecting subsea and surface components of the operation. Thus, it is common in such operations to provide some means for disconnecting the lower riser assembly from the blowout preventer. Many other such situations in different industries and in various remote or hazardous locations can be envisioned which require the connection and disconnection of equipment.
At a subsequent time, when it becomes necessary to reconnect such equipment, it is frequently of crucial importance that the components to be connected be carefully aligned before those components are allowed to contact each other. Otherwise, the necessary connections between certain pieces of equipment might not be properly coupled. In the instance of a blowout preventer and lower riser assembly, for example, typically a number of hydraulic lines must be connected between the components. Furthermore, the weight of the equipment to be reconnected might cause considerable damage to the components if a precise alignment were not achieved before the separate components are allowed to come into contact.
Frequently it is difficult or undesirable to dispatch personnel to such a remote location to manually align and connect such components. Thus, it is necessary to provide some form of automatically or remotely aligning and connecting the components. Various forms of such automatic aligning and coupling means are known. In the undersea oil production industry, for example, a combination of sonar and television systems are frequently used to approximately locate the separate components relative to one another. In this technique a television camera and sonar transmitter mounted on the piece of equipment to be reconnected, such as a lower riser assembly, transmit signals to a surface location, where operators may manipulate connecting equipment, such as a pipe string, to approximately locate the disconnected equipment relative to the associated undersea comoponent, such as a blowout preventer stack.
Once the separate components have thus been approximately aligned, a centering peg or cone or some such device mounted on one of the components is brought into contact with a portion of the second component adapted to receive that device, thereby achieving the axial alignment of the two components. Once axial alignment has been achieved, however, the parts frequently must be rotated to accomplish the proper rotational orientation of one part with respect to the other in order for proper connections to be made between the components.
In one known design, this rotational alignment is accomplished with a device known as a latch bumper head. In this technique, a vertical groove is provided within a cylindrical element which is attached to one component of the equipment, while a second component of the equipment includes a corresponding spring loaded key member. After initial alignment by sonar and television to achieve axial alignment, the component to be connected, such as a lower riser assembly, is rotated about the vertical axis by rotating connected equipment at the surface, such as a pipe string. When the spring loaded key engages the groove provided, the key catches in the groove and rotationally aligns the first component, such as a lower riser assembly, with respect to the second, such as a blowout preventer stack. The components then are allowed to move more closely together so that hydraulic and other connections between the two components may be engaged. In another similar design, after the first and second components are axially aligned, the upper component is again rotated by rotating the connecting equipment at the surface. In the second design, a spring loaded pin is provided on one component. When the components have reached the point of proper rotational alignment, the spring loaded pin drops into a corresponding hole which is provided in the second component, thereby locking the two components into the proper rotational position.
The devices discussed above are capable of accomplishing the desired axial and rotational alignment between two related parts which must be connected. The devices which are known, however, are subject to some disadvantages. These devices, for example, require for their operation the rotation of associated equipment, such as a pipe string, at the surface of the water over the blowout preventer, requiring provisions to be built into such equipment to adapt the equipment to be so turned, and further requiring some powered means at the surface to provide the rotational force. Since a considerable amount of equipment might need to be rotated, this requirement can impose significant costs in additional equipment to be provided for such an operation. Thus, it would be advantageous to provide such an aligning and connecting apparatus which would not require rotation of the surface equipment to achieve automatic rotational alignment and further would not require a powered means at the surface to operate such equipment. In particular, it would be advantageous to provide such an apparatus which is capable of utilizing gravitational forces to motivate the rotational alignment function.